1. Field of the Invention
This invention pertains to wrapping machines and more particularly relates to high speed twin lane wrapping machines which simultameously entube pairs of transversely spaced articles in a web of wrapping material.
2. Description of Prior Art
Single lane wrapping machines such as disclosed in U.S. Pat. No. 2,882,662 to Campbell that issued on Apr. 21, 1959 are well known in the art. The Campbell wrapper lowers a web over a continuously moving row of spaced articles. The web is then folded under the articles and the overlapping edge portions are longitudinally heat sealed together by a rotary sealer to form a fin. The single tubular web is then transversely severed by rotary crimping and severing rolls of the type disclosed in Campbell U.S. Pat. No. 2,546,721 which issued on Mar. 27, 1951 or by the type of sealer disclosed in the aforementioned Aterianus application thereby providing individually packaged articles.
U.S. Pat. No. 2,565,444 to Waters which issued on Aug. 21, 1951 discloses a machine which receives a web of thermosealing wrapping material and forms upwardly opening W-shaped envelopes therein. Articles are dropped from a hopper into the two downwardly inclined envelopes which are thereafter longitudinally and transversely sealed. The so formed and filled packages are then longitudinally and transversely severed to provide a plurality of filled containers.
Another type of twin lane wrapping machine is disclosed in our U.S. Pat. No. 3,581,457 to Gerlach et al. which issued on June 1, 1971. This patent discloses a machine wherein a web of wrapping material is drawn downwardly over two rows or lanes of longitudinally and transversely spaced articles. The longitudinal edges of the web are then folded under the articles and are longitudinally heat sealed directly to a central portion of the web disposed between the rows of articles to provide two rows of entubed articles. The web may be longitudinally perforated to provide a tear strip prior to being folded and longitudinally sealed. The spaces between pairs of articles are thereafter transversely heat sealed by heat sealers on endless conveyors, are crimped, and are subsequently severed from the web to provide packages containing pairs of articles.
Heinzer U.S. Pat. No. 3,760,559 which issued on September 25, 1973 discloses a double lane wrapper wherein the web is moved downwardly over, not upwardly under, the articles. The longitudinal edges of the web are then folded under the articles, are longitudinally sealed and severed and are thereafter transversely sealed and severed.
Brook et al. U.S. Pat. No. 3,110,142 which issued on Sept. 25, 1961 discloses a single lane, not a twin lane, wrapping machine which moves articles onto a web of material which is then formed into a tube by applying heat to the web. The tube is thereafter transversely severed and either twist sealed or heat sealed to seal each article in a separate package.